I'm not sure how you can say with such confidence that she wasn't run over by anything, but in any case, yes, having broken ribs hurts like the dickens and it doesn't take that much to get them (I got one from coughing really hard). Do you have link for the bit about broken ribs? It would be great to dispel the myth that many of us have seem to have incorporated into our inner narratives of what happened.
This headline says, "shattered bones" (though the article only refers to many broken bones):
http://www.readthehook.com/68346/shattered-bones-harringtons-say-morgans-killer-violent-sadistic:
"Her parents desperately wish it weren't so, but they say they're convinced: Morgan Harrington suffered before she was killed.
On the five month anniversary of the Virginia Tech student's disappearance and less than two months after her remains were discovered in a remote area of a southern Albemarle County farm, her parents, Dan and Gil Harrington, spoke to reporters in front of the John Paul Jones Arena, where Morgan attended an October 17 Metallica show the night of her disappearance, to beg anyone with information about the case to come forward and to urge caution in the Charlottesville community.
"A monster walks among you," Gil Harrington says, calling her daughter's killer a "violent, sadistic and dangerous man...He chooses to kill in a savage and brutal way," says Gil Harrington, an oncology nurse, of her daughter's killer, "to break her bones before he murdered her." Dan Harrington, a psychiatrist, confirms that his daughter's skeleton showed "brutal damage."
While the Harringtons won't say which of Morgan's bones were broken–- and acknowledge that they do not yet know her actual cause of death, pending the release of the official autopsy report–- they remain convinced that the person responsible is an experienced criminal and may be a convicted sex offender."